irratiic router resets

Hi, My speeds have over a few days now been erratic, At one point down to 3Mbps,I contacted support via live chat and the gentleman i spoke to said he could see why and reset something ( not quite sure what) but the speeds have raised once more, the thing I have noticed is the router has reset itself a few times without me touching it, I have also noticed when checking my bandwidth viewed in the router readout has dropped from nearly 25000 to 22.792 kbps also estimated line speed dropped from 21mbps to 19. My speeds have reached 18 Mbps where I was getting on a regular basis 19 going onto 20.When I did checks with BT Test results the ip profile is 20.11Mbps, I know some site members would say 18Mbps they would be happy but I have been blessed with good speeds since joining Plusnet and living practically next door to the exchange helps but cant understand why these blips and router keep resetting, I think its reset 3 times today.I have noticed that I've ended up on quite a few different gateways over the last month or so and I've just put it down to BT works I'm notified by Plusnet support emails about those works .I tried phoning Plusnet support but was told a by automated message waiting times is 30 min.I thought i'd post here and see if Plusnet support had any answers.Regards Jono